Spark-plug.



J. A. & B. A. JEFFERY.

SPARK PLUG.

APPLICATION-FILED SEPT.23| 1908. RENEWED JULY l0, 19|6.

Patented Jan. 30, 1917.

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M JEFFERY AND BENJAMIN .ALFRED JEFFERY, 0F NEWARK, NEW I amasar.

SPK-PLUG.

Application led September 23, 1908,' Serial No. 454,401.

To all whom t may concern:

Be it known that we, JOSEPH A. Jnrrnnr `and BENJAMIN A. JEFFERY, of Newark, in 'the county of Essex, State of New Jersey,

have invented certain new and useful lmprovements in Spark-Plugs, of which the following is a specication.

This invention relates to certain new and useful improvements in spark plugs.

The invention has for its object the production of a simple, inexpensive and highly elicient device of this character in which the conductor or terminal wire is firmly embedded inthe insulating body or block in such manner as to. provide an absolutely gas tight union with said insulating body without the use of cement, or the like.

lt has beenfound that an air gap greatly increases the efficiency of a spark plug by introducing suficient resistance in the secondary circuit to maintain the potential of the latter when `accumulations on the surface of the insulating block would tend to reduce the resistance in .the circuit. The objection to this air gap is the fact that the resistance is varied by the formation of metallic vapor during the passage of the current; and also the -diculty of sealing the gap so as to prevent oil or otherforeign matter from reaching it and either lowering 0r raising the resistance.

lt is one of the objects of the present invention to provide a resistance that will prevent the formation of an arc and which, as a result, will not be materially affected by any matter that may come in contact with it.

A further object is to provide an im# proved binding post, and simple and emcient means for securinyg the same in position.

A further object is .to provideimproved means for establishing a gasftight joint between the insulating block and its supporting bushing. Y i

rlhe invention will be hereinafter fully set forth and particularly pointed out in the claims. Y A

In the accompanying drawing z-Figure 1 is a longitudinal sectional view .illustrating one embodiment ofA our improved spark plug. Fig. 2 is a similar view lof a slight modification thereof. Fig. view of an additional modification. Fig. 4 is a detail perspective view of the binding Speeication of Letters Patent.

3 is a sectional' Renewed July 1o, 1916. serial no. 108,451.

post. Fig. 5 is a view of the securing cap rammen aan. so, 1era.

therefor. Fig. 6 is a sectional View of the binding post.

Referring to the drawing, 10 designates the insulating block provided with a longitudinal bore 11 leading in from one end, the other end being closed or made solid, as indicated at 12. rlhe end provided with the Abore is tapered at 13 and provided with an annular rib 14, the other end of said block being provided with a head 15. rlhe terminal wire 16 is embedded at its upper end in the closed portion 12 of the block 10, the

lower end of said wire extending through bore 11 and protruding from the latter. rlhe rib 14 is engaged by a cup-like ring r17, the portion of said ring lextended above said rib 14 being filled with any .suitable or preferred packing 18. rlhe rounded portion of ring 17 forms a shoulder which is adapted to rest upon a complemental internal shoulder 19 formed in the usual supporting bushing 20, and the block 10 is rigidly held in position by means of a second 'bushing 21 engaging the inner wall of bushing 20 and provided with a reduced edge 22 arranged to fit within ring 17 and compressthe packing 18. In this manner the block 10 is adjustably supported in the bushing 20, theY ring 17 provlding a bearing that will permit a limited adjustment'of the block by a rocking movement thereof before bushing 21 is screwed home. In this connection it will be noted that a decided advantage is gainedby vreason of the fact that'the packing 18 and ring 17 Abecome practically a part of the insulating block, and these parts are all held together when the plug is separated for it carries with it the insulating block and all of its adjuncts. 'llheV ground terminal is formed by a suitable wire 23 secured to.

bushing 20.

The binding post 24 is provided with a i threaded shank and a head 25, the latter being slightly cupped on its underside as indicated at 26, and provided/with an external angular portion 27. ln the drawing we have illustrated the angular portion 27 as square, but it will be understood that we do not desire to limit ourselves to any particular shape. The binding post is secured in position by means of a cap 28 provided with an angular opening 29 corresponding in shape to the angular .portion of head 25 and constructed to receive said angular portion, the lower edge of saidcap being turned over the head 15. Abinding nut 30 works on the threaded shank of the binding post and is preferably provided with a head 31 to receive any form of terminal clip,4if the same should be used. Or, if desired, the termi? nal may be clamped in the vusual .way between the nut 30 and cap 28.

-In practice itis of decided advantage to provide a gap at some point in the circuit through the spark plug and this has usually been done by providing an air gap. We have found, however, that excellent results .are secured by causing the current to pass through a small body of high resistance. Wetherefore interpose a thin washer or disk 320i high resistance material between the binding post 24 and wire 16, and'within the recess or chamber 26 of the binding post. We have secured excellent results with a disk of carborundum, but do not desire to I' limit ourselves to any specific material.

ductor 34 between 'the wire 16 and the In Fig. 2v we have illustrated a slight modification which consists-in reducing the diameter of wire 16 near its end, as indicated at 33. In Fig. 3, a like result is attained by interposing an independent con en of the-block 10.

It is well known in the art that while attempts have been made to bake a conductor wire within an insulatingblock, such attempts have been without practical success for the reason that the shrinkage of the por+ celain in baking is such thatl the insulation draws away from the wire, thereby destroy'- ing the gas tight union that is so necessary in devices of this kind. Another disadvantage encountered in baking in the terminal wire is that the wire anneals -under the temperature of ,the kiln and becomes so softened thatit will buckle when the porcelain commences to contract 'or vitrify, thereby spoiling thev shape of the plug and rendering the same useless. We have found vthat these disadvantages are overcome by using 'a .wire containing nickel and chromium.

' The `'surface kof this "wire during the firing Aes process effects a firm chemical union with the insulator throughout -its length, which union is absolutely gas tight. By this means a, wire may be used of sufficient diameter to be left above the face of the insulator and at thesame time, by reason of its size, resist thedisintegrating actionof the spark. This alloy also possesses the additional advantage that it will not anneal or soften to any material degree under the temperature developed in the baking process, thereby-aiding in holding the block to its proper shape.

The importance of this feature lies in the fact that all porcelains of great heat resisting qualities or those that will resistvthe extremely rapid changes of temperature must contain a lesser amount of Hint, or similar ingredients, such ingredients being added to make the articles fire straight but at the expense of the 'qualities 'so desiredin an insulator for spark plugs. It willl be noted, however, that we do'not desire to limit ourgood results have also been secured with other' metals. A further advantage is gained by arranging the disk of high resistance material in the circuit. It is Well known that the ordinary air gap employed for this purpose is usually filled with metal vapor during theelectrical discharge, thus in a measure defeating the object of the gap. The high resistance disk prevents the formation of such vapors, and at the same A selves to the specific alloy mentioned, as-

time provides a path of unvarying resistance equal to that of the ordinary spark gap. It vwill also be noted that in the spark plugs now in general use much trouble is eX- perienced by the loosening and disarrangement of the central electrode and gasket when the nuts, etc., used to fasten the bat# tery terminal to the plug, are tightened down finally. This trouble 1s eliminated by 1. In a spark plug, an insulating block, a4

conductor carried thereby, an electric-terminal carried by said block andin circuit with said conductor, a gap being formed between said terminal and said conductor, andan arc-preventing resistance material in said gap to prevent passage of any currents but those .of high potential.

' 2. In a spark plug, an insulating block, a conductor carried thereby and forming part of the circuit through said plug, 'a gap being formed in said circuit, and a solid body of arc-preventing high resistance material in said gap to prevent the passage of any cur.- rents but thoseof high potential.

3. -In a spark plug, an insulating block, a

' conductor carried thereby and forming part ofthe circuit through said plug, a gapbeing',

formed in said circuit, and a solidbody of carborundum in said gap to prevent the passage of any currents but those of high potential.

4. In a spark plug, insulating block, a

conductr carried thereby and forming part Lai-agri of the circuitv through said plug,`a ap being formed in said circuit, a solid bo y of arcpreventing high resistance material in said gap to prevent-the passage of any currents ,but those of 'high potential, and means for preventing lateral displacement of said high resistance body.

5. In a spark plug, an insulating block, a conductor carried thereby, a binding post resting directly on the en d of said block and separatedfrom the end of said conductor by a space, means in said space for interposing a uniform resistance in the circuit to said conductor, and an independent cap for securing said binding post to one end of said block.

6. In a spark plug an insulating block, a conductor carried thereby,"a binding post independent of said conductor and having an enlarged head resting on the face of one end of said block, and a cap independent of said binding post for clamping the latter'to said insulating block, said binding post and being provided with complementa] means for preventing relative rotation.

7. In a spark plug an insulating block, a conductor carried thereby, a binding post independent oi said conductor having an enlarged head resting on the face of one end' of said block, independent means for clamping the enlarged portion of said binding post to said block, and means for preventing relative rotary movement of said binding post and said insulating block.

8. In a spark conductor carried thereby, a binding post having an enlarged head resting on one end of said block, said head being provided with a cavity in its under face coperating with the end of the block to form a closed chainber, means in said chamber for interposing a uniform resistance in the circuit to said conductor, and means for securing said binding post in position.

.9. In a spark plug, an insulating block, a conductor carried thereby, a binding post in circuit with said conductor andhaving an enlarged head resting on one end of said block, and a cap fitting over said head and secured to said block.

10. In a spark plug, an insulating block, a conductor carried thereby, a binding post in circuit with said'conductor and` having an enlarged head resting on one end oiy said block, a cap fitting over said head and secured to said block, and means for preventing rotation of said binding post with relation to Isaid cap.

11. In a spark plug, an insulating block, a conductor carried thereby, a binding p ost jin circuit With said conductor and having f an enlarged head resting on one end oi said being' provided with an block, said head and a cap fitting 4over said angular portion,

head and secured Vto said block, said cap cap plug an insulatingblock, a

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being provided with an angular opening lclonorming tothe angular portion of said 12. In a spark plug, an insulating block, a conductor carried thereby, a binding post in circuit with said conductor and having an enlarged head resting on one end of said having an enlarged head'resting on one end of said block, means for securing said post in position, and a body of material of high resistance interposed between said head and the contiguous end of said conductor.

14. In a spark plug, an insulating block, a conductor carried thereby, a binding post in circuit With said conductor and having an enlarged head resting on one end of said block, said head being provided with a cavity, ineans for securing said binding post in position, and abody of material of high resistance located in lsaid cavity.

15'.\In a spark plug, an insulating block, a conductor carried thereby and having one terminal Hush with said block, a binding post' resting directly on` the end of said -block adjacent said flush terminal and provided with a chamber over said terminal,

and in eans for securing said binding .post in position.

16. In a spark plug, an insulating block,

a conductor carried thereby and having one terminal flush with one end of said block, a binding post secured to said block and ad]acent said flush terminal, and a body of material of high resistance interposed between said binding post and lsaid Hush terminal.'

17. In a spark plug, an insulating block, a conductor carried thereby and having one terminal flush with one -end of said block, a binding post having a head secured to' said block adjacent said `Hush terminal and provided with a cavity inits under face cooperating With the end of the block to form a closed chamber, and means in said chamber for interposing a uniform resistance in the circuit to said'conductor.

18. A. spark plug comprising an insulating block, a conductor carried thereby, packing encircling said block, a supporting bushing forming part of the ground -terminal, a bearing., cap inclosing said packing and wholly inclosed Within said bushing, and a second bushing having one edge fitting Within said cap to compress said packing. A

19. A. spark plug'comprising an insulating block, a bearing cap surrounding the same and provided with a smooth exterior surface, an annular space being formed between said block and said cap, and packing material forced into said space to frictionally unite said block and cap to form a single unitary device. 'v

20. In a spark plug, an insulating block provided with an annular rib, a bearing cap surrounding said rib and provided with a -smooth exterior surface, an annular space being formed between said block and said cap adjacent said rib, and packing material forced ,into said space to frictionally'unite said block and cap to form a single unitary device.

21. In a spark plug, a solid insulating block provided with a longitudinal bore for a portion of its length, and a conductor yvire having its sparking terminal projectlng from the open end of said bore, the

other end of said conductor being embedded within the solid portion of said block and Y 22. .In a spark plug, an insulating block,

a conductor carried thereby, a binding post in circuit with said conductor and having an enlarged angular head supported by one end of said block, anda cap having an angular portion-engaging said head, and secured to said block.

.In testimony whereof, We have signed this specification in the presence of two subscribing witnesses. Y

JOSEPH ARTHUR J EFFERY. BENJAMIN ALFRED JEFFERY.

Witnesses:

MORTIMER CLUFF DEWm'r, JOSEPH S. STEPHEN. 

